It is known from Mori et al U.S. Pat. No. 4,111,879 that resin-based coatings or paints having in them certain amounts of N-phenyl maleimide (hereafter sometimes "NPM") will be effective in reducing the population of barnacles compared to articles submerged in a marine environment and not coated or painted with them. The NPM is not copolymerized with methyl methacrylate or any other monomer; rather, the "resin" is preformed.
NPM has been introduced into unsaturated polyester compositions through copolymerization with the styrene in which the polyester is normally dissolved. See Piermattie et al U.S. Pat. No. 4,983,669. It has also been copolymerized with ABS, styrene, and methyl methacrylate. See Nield U.S. Pat. No. 3,676,404, Dean U.S. Pat. No. 4,696,978, and Dean U.S. Pat. No. 4,701,493. The copolymers described in the Nield and Dean patents are useful in the present invention, and the entire subject matter of them is incorporated herein by reference. However, we are not aware of its use as a comonomer in polymethylmethacrylate to inhibit the settlement of marine organisms.